High voltage control in television receivers



April 23, 1957 J. F. BIGELOW HIGH VOLTAGE CONTROL IN TELEVISIONRECEIVERS Filed Aug. 24,1953

, Y 5 I (I MG SXQQ l m I Inventor United States Patent I'HIGH voLAGEeoNT-RoL IN-TELEwsroN -REGELVERS 1 :Jn n 1? si ht-w, @B e si a 5 1. si to a fl .-.Maa fac uringaC mpa yrwal a a arp-9 tion of Delaware i Y IAppiica'tiontAhgusbM, 1 953, 'Serial'rNm- 3U6fl29 iaae m relat -e27)ts-ta tei i iq mat re til-h r iu y nuimpqr a t-ohi c :Q th ;pre en ivento go de+avhighvvoltage control circuit-wvhi chsis in anp a sah aatfia r n i rw s s fiein r figmw i .a' sith use-s e my w rm ll e e inveti t me id t q -whk s m r ts fieie tlby 1: teeatro lingzth lie, 1

produce the charge portion of 'the sweep drivefjignal. As the discharge-tullec crnducts, "the storage gcondenser "discharges to; produce thedischarge portion of thejsweep drive signal. 'The conduction of thedischarge 'tube'is controlled by the-pulses produced by-tltehoriontahsweep pulse-oscillator.

5 111 order to cont-r01 :the :current ffiow ito .=ai= higlr voltage.transformer, a' switchingicircuit 'isaprcviderit .EhiSWltQhp ie f rmvth d scha s z ircuit-t 19mins t ms 't -v V 1 2,790,108 Patented Apr.23, 1957 t'ijqnal, rectifying circuit in a. power vsupply circuit isprovided. In the; preferred "embodiment, a conventional picture tubeiortelevision receivers is connected tothe output of the 'power vsupplycircuit.

,Forregulating the output ,voltageofthe. power supply, anautomatic-regulating ,circuit is provided,- comprising ,a;voltagecontroltube arid a'feedback-orbleeder circuit.

llfheiieedbackor bleeder circuit is connected 'to the' outputdffthepbwer-supplyand tothqg'rid of the voltage co ltuhe. Theoutputdoffthe voltage control tube is fiionnected totheresistance-capacitance network of the "discharge circuit. {As .theoutput voltage .of the power supply circuit ,v'aries ithejdirfectcurr'entvoltage applied to'the grid of the ,voltagetcoiitroltube varies directly It rewi -h L jA ccordingly, [the voltage control,tube is in the dis cha1 ;"ge.c uit of the istorage condenser. As a.result ereot, the grid of thew-voltage control tube becomes rnore p ove, .the discharge ,portion tof the. sweep, drive signalhas'a'lessenar'nplitude. "Consequently, the rate of changeinnvoltagewith respect. to time .of .thepositive portion of thefdischargeportion decreases. Thus, the ,vo'ltage jindugfid in the selidary Lwinding o'f .fthe high l vo age tra sformer decreases.Conversely, as'.'the,gi'id I'lt ge' control'tubelbecomes lesspositive,:the disge portion or thej-sweep di'ive signalg haslagreater Laplittide. Consequently, the rate.. of-. change in voltage th-re'spectftotirneflo'f .the .positive,portion of gt he dis- ???582 Pqflionincreases'. Thus, the "voltageinduced in "the secondary' winding .of ,th e high ,voltage transformer oh i wa sepa at d-with n he tpewe supplyrather than controllipgqariable loss ,thrqugh a' ranit ish vnl esesq incea e fer ringgnow to Figs. ,1 and:2, a.su itable source of p',seen'ergy'is producedby all-generator .10, .which i-n ftihe pre'ferredembodiment, is. a horizontal sweep oscilllato'r. t

Eorj producing a sweep drive voltage, as, showuinlFig. T2, ,as1iita6le;.1discharge circuit ll is provided comprising [a conventionaltrio'de ,tube 12, designated discharge tube. The discharge.tube 12 base,gi'id 11-3 :lihreof connected to the, output of the horizontal sweeposcillator 10 Included withinthe discharge cii cui t Il'is'aresistanceica'paciltafice network comprising storage" condenser/'14 andja barging .resistor '15. ,The di'shargeftube "12 is plate currentcutofr'. tVlll'iile thldisharg'e tube A s l nonconducting, the,tstoragencondejn'ser' 14 charges in series with resistor 15 toproducethe charge portion of the sweep.drivesignal, ,since there is apotential ,difierfence s lqfs esi v Th '.pd ent a1 di fere ce ,ab osresistor 40 is I produced by the currentfflow through tube .18.

thegenerator 10, discharge tuhe' '12 conducts. Asfa're's'ult thereof,stor'a'gefcondenser 14 "discharges, to produce the discharge pontion ofthe sweep drive signal, through the tithe 12"jto grqund and returning tocondenser jl over a network compi'isinglresi'stor 49, tube .18, tube 17and 'The sweep drive signal, as it appears across grid resistorfna,isshown in Fig. 2.

Hits "to benoted that the sweep drive signal is "a saw- "tooth waveform"having 'a negative pul'se superimpo'sied ilie'reoni 'Thesawtoothpoif'tion is produced-by the condenser 14,=1andthe negativepulse 'Jfis produedfbjy*the *i'EistOr'fIO and the plate-"cathoderesistance of tube 18. -The'point marked B+, common to resistors-" 15,38and "3e30, is at C. ground potential, because 0f the lowinternal:impedauce inherent" in a 13+ powersupply.

The cathode-of tube 18 is a'tground because of the char- -acteristics oftube-17, which appears to an A. (3. signal -as a large condenser. inview of 'the' for'e'going, tube '13 V is in parallel with resistor 40for A. C. signals. V t

As a'positive pulse. is fed to-the discha'rge'tube 12'from 3 tance ofthe charge resistance-capacitance network because of the relativelylarge value of the resistor 15, which is approximately 250,000 ohms.However, it does appreciably affect the effective resistance of thedischarge resistance-capacitance network because of the switching tube20 is connected to a blocking condenser 21, v I

which in turn is connected to the storage condenser 14, chargingresistor and the plate 16 of the discharge tube 12. The switching tube20 has the plate 23 thereof connected to the primary winding 19a of thehigh voltage transformer 19; The switching tube 20 is biased so as toconduct only during the positive portion of the sweep drive signal,drawing its plate current through the pri- 'mary winding 19a.

The period of'itime in which the switching tube 20 changes from a stateof conduction to one of non-conduction is a portion of the retrace time.

' ,For providing direct current voltage to an output,

which, in the preferred embodiment, is a picture tube 24,

a conventional power supply circuit 25 is provided. The power supplycircuit 25 comprises a second section 26 of the primary circuit of thehigh voltage transformer 19 which is connected to a plate 27 of arectifier tube '28. The cathode 29 of the rectifier tube 28 is connectedto a filament winding 30 of the high voltage transformer 19. The. directcurrent plate voltage path for tube 20 is as follows: B+, winding 42,tube 44, coil 45, winding 19a and the plate of tube 20. I For regulatingthe voltage output of the power suppl circuit 25 by controlling thevoltage applied thereto, a voltage control circuit is providedcomprising a feedback or bleeder circuit 31 and the triode tube 18,desig- 1 The feedback circuit 31 is connected to the output of the highvoltage power supply nated voltage control tube.

through a dropping resistor 32 and comprises a variable resistor 33 anda resistor 34. The voltage control tube of the voltage control tube 18decreases. Consequently, the current flow through the tube 18 decreases,causing the cathode-to-plate resistance of tube 18 to increase. As aresult thereof, the effective resistance of the paral lel connection,resistor 40 and tube 18, increases. Thus, the amplitude of the pulseportion of the discharge portion of the sweep drive signal increases, asshown by solid lines in Fig. 2. Consequently, the discharge portion ofthe sweep drive signal, during the positive portion thereof, has anincreased rate of change with respect to time. Accordingly, the voltageinduced in the secondary winding 26 of the high voltage transformer 19increases.

In the preferred embodiment, during the retrace period, scanning voltagefor the picture tube 24 is provided by a horizontal sweep circuit 41'.The horizontal sweep circuit comprises a secondary winding 42 of thehigh voltage transformer 19 to produce alternating current oscillations.Connected to the secondary winding 42 is a deflection yoke 43, whichproduces the magnetic scanning field for the picture tube 24. Fordamping the oscillations, a damping tube 44 is provided having the 18has a grid 36 thereof connected to the feedback resistor 34 of thefeedback circuit 31. A cathode 37 of the voltage control tube 18 isconnected to the conventional constant voltage tube 17 and to B+ througha dropping resistor 38. The plate 39 of the voltage control tube 18 isconnected to the storage condenser 14 and the plate current supplyresistor 40 of the discharge circuit 11.

Accordingly, the voltage control tube 18 and resistor 40 are connectedparallel in the discharge'circuit of the storage condenser 14, andfunction to control the pulse portion of the discharge portion of thesweep drive signal, in a manner previously described. A

As the voltage in the output of the power supply circuit 25 varies, thedirect current voltage across the feedback circuit31varies directlytherewith. Accordingly,

as the voltage output of the powersupply circuit 25 in- -c'reases,'thepositive potential-applied to grid 36 of the voltage control tube 18increases. As a result thereof, the current flow through the tube 18increases, causing the .cathode-to-plate resistance of tube 18 todecrease.

:Consequently, the effective resistance of the parallel connection,resistor 40 and tube '18, decreases. Thus, the amplitude of the pulseportion of the discharge portion of the sweep drive signal decreases, asshown by dotted lines in Fig. 2. As a result thereof the discharge portion of the sweep drive, signal, during the positive portion thereof,has a decreased rate of change with respect to time. Accordingly, thevoltage induced in the secondary winding 26 of the high voltagetransformer 19 decreases.

As the voltage output of the power supply, circuit 25 decreases, thepositivepotential applied to :the grid 36 signal for controlling theoutput voltage for said power supply circuit, and a voltage regulatingcircuit connected to said discharge circuit and responsive to variationsof the output voltage of said transformer for varying said sweep drivesignal, thereby regulating the output voltage of said power supplycircuit.

2. In a voltage control circuit, a generator providing a source ofelectrical energy, a discharge circuit responsive to said generator forproducing a sweep drive signal,

a power supply circuit comprising a high voltage transformer, an energydeflection circuit adapted to be energized by way of said transformer,an oscillation reducing circuit forming an extension of said energydeflection circuit, a switching circuit additional to and distinct from,said oscillation reducing circuit and responsive to said sweep drivesignal for controlling the'output voltage for said power supply circuit,a feedback circuit connected to the output of said transformer, and avoltage control tube interconnecting said discharge cir- 55 p of outputvoltage of said transformer for varying said sweep drive signal, therebyproviding voltage regulation cuit and said feedback circuit andresponsive to variations for said power supply circuit. p v

3. In a voltage control circuit, a generator providing a source ofelectrical energy, a discharge circuit responsive to said generator forproducing a sweep drive signal having a discharge portion thereof, apower supply circuit comprising primary and secondary transformerwindings,

an oscillation damping circuit linking said windings, a switchingcircuit additional to and distinct from said os- -cillation dampingcircuit and responsive to said sweep drive-signal'for controlling theoutput voltage of one of said transformer windings, a voltage regulatingcircuit having a feedback circuit connected to-the output of said powersupply circuit for providing a feedback voltage, and

a voltage control tube in said voltage regulating circuit connected tosaid discharge circuit and responsive to variations of feedback voltagefor varying the amplitude of the discharge portion of saidvoltage'control "signal for amiss e sisaalt t, g e t, w resales theculpri swear i d power sppply circuit 9 21 ct d la tltsss+ 9ntm si sgttase sratpt nr i a pa source of lectrical'eneirg'y, adischai'gerespiinsive to said generatpr for prodpcing a sweep drive signal, adischarge'i sistanc capacitance Het'wdi'lE iii saiddischarge circuit dasaedi s stseirsrt q sai Sweep drive lgr tal a power supply circuit compa highyolt circuit responsivelitosaid sweep LL11 a is at tqltasafigr, sa distinct from saidoscillation damping circuit and respon- "cuitfand avoltage regulating circuit connect sive to said sweep drive signal forcontrolling the output discharge circuit and responsive to variations ofthe outvoltage of said power supply circuit, a voltage regulating 1 putvoltage of said power supply circuit for varying the circuit having afeedback circuit independent of said ennegative pulse of said sweepdrivesignal, thereby reguergy deflection circuit, and a voltage controltube'in said lating the output voltage of said power supply circuit.voltage regulating circuit connected to said discharge re- 8. In avoltage control circuit, a generator providing a sistance-capacitancenetwork and responsive to variations source of electrical energy, adischarge circuit responsive of feedback voltage for varying theeffective resistance to said generator for producing a sweep drivesignal comor said discharge resistance-capacitance network, therebyprising a sawtooth waveform having a negative pulse controlling the rateof change of the discharge portion of superimposed thereon, a dischargeresistance capacita'nce said voltage control signal for regulating theoutput voltnetwork in said discharge circuit providing a discharge ageof said transformer. portion and negative pulse for said sweep drivesignal, a

5. In a voltage control circuit, a generator providing power supplycircuit comprising primary and secondary a source of electrical energy,a discharge circuit respontransformer windings, an oscillation dampingcircuit linksive to said generator for producing a sweep drive signal,ing said primary and secondary windings, a switching a dischargeresistance-capacitance network in said discircuit additional to anddistinct from said oscillation charge circuit providing the dischargeportion of said damping circuit and circuit responsive to said sweepdrive sweep drive signal, a power supply circuit comprising a signal forcontrolling the output voltage of said power high voltage transformer,an oscillation damping circuit Supply circuit, a voltage regulatingcircuit having a feedincluding a portion of said transformer, aswitching cirback circuit connected to the output of said power supcuitadditional to and distinct from said oscillation dampply circuit, and avoltage control tube in said voltage ing circuit and responsive to saidsweep drive signal and regulating circuit connected to said dischargeresistanceconnected to said high voltage transforme for varyingcapacitance network and responsive to variations of feedthe rate ofchange of magnetic flux in'said transformer back voltage for varying theamplitude of said negative for controlling the output voltage of saidpower supply pulse produced by said discharge resistance-capacitancecircuit, a feedback circuit connected to said power supnetwork, therebycontrolling the rate of Change Of the ply circuit for providing afeedback voltage, and a voltage i ch rg p i n of said voltage controlSignal for regucontrol tube connected to said discharge resistance-ca-40 lating the Output Voltage of Said Power pp y circuitpacitance networkand responsive to variations of feed- 9. In a voltage control circuitfor a load whose operaback voltage for varying the effective resistanceof said tion req the delivery of Sweep drive Signals thereto, dischargeresistance-capacitance network, thereby vary- 'the combination with saidload of a generator providing ing the amplitude and rate of change ofthe discharge a source of electrical energy for said sweep drivesignals, portion of said sweep drive signal in order to vary the m sincluding a discharge tube and an network rate of change of magneticflux in said transformer to responsive to operation of said generator toregulate the provide voltage regulation. transmission of said sweepdrive signals, a power supply- 6. In a voltage control circuit, ahorizontal oscillator controlling Sw tube having its Plate circuitleading for providing a series of pulses, a discharge circuit reto saidload to energized, also having its Control sponsive to said series ofpulses for producing a sweep grid responsive to the Values Prevailing inSaid drive signal, a charge resistance-capacitance network in Work, aVoltage regulating tllbe having its Plate circuit said discharge circuitproviding the charge portion of said included Within Said network, andits grid Circuit sweep drive signal, a discharge resistance-capacitancenetdistinct from h said discharge tube, and means to work in saiddischarge circuit providing the dischargepori excl-lawn Voltage SaidVoltage regulating tube ti-on of said sweep drive signal, a switchingcircuit con- E accordance, wlth Variations in the amount ductive inresponse to positive portions oftsaid sweep Power dehvered to d drivesignal comprising both the charge and discharge 10. In a voltage controlcircuit for a load whose operportion thereof and non-conducting duringthe negative anon 'i P y of sweep dnverslgpals h portions of said sweepdrive signal comprising both the the icombmatwn with sa1.d load of.means mcllldmg charge and discharge portions thereof producing aretrace 1 i i k fqr ltegllllatmg the dehvery of i sweep time duringsaidnon-conducting period, a power supply S i to sald a sourcepfhopgratmg aycircuit providing a high voltage output voltage in refi i 5. l mg g 5 3mg sponse to rate of change-of current flow from said switche wery o Salopera mg power 0 Sal 0a an means for controlling the excitation voltageapplied to said switch tube, said, means including a voltage regulatingtube having its grid-cathode circuit across said load and responsivesolely thereto, and having its plate circuit in- .cluded' within saidR-C network. 7

' 11. In a voltage controlling circuit, a generator providing a sourceof electrical energy, a discharge circuit ing circuit, a picture tubehaving the high voltage therefor supplied by said power supply circuit,an electron beam deflection circuit associated with said picture tube,

a feedback circuit independent of said electron beam defiection circuitbut connected to said power supply for providing a feedback voltage, anda voltage control tube connected to said discharge resistancecapacitance not including a discharge tube and an network respon; workand responsive to variations of feedback voltage i -to said generatorforproducing a sweep drive signal, for varying the effective resistance ofsaid discharge rea voltage regulating tube having its plate circuitdirectly sistance-capacitance network, thereby varying the amconnectedwith said R-C network, and its grid circuit plitude and rate of changeof the discharge portion of 7 distinct from said discharge circuit, apower supply-controlling switch tube having a plate circuitleadlng to aload to be energized, and also having a control grid responsive to theR-C characteristics of said network, means for storing energy in saidR-C network betwen's uccessive conducting periods of said dischargetube, and means for controlling the magnitude of the stored energycharge in accordance with the excitation voltage applied to said controlgrid. a

12'. In a voltage control circuit, a generator providing af'sourceofelectrical energy, a discharge circuit including an R-C networkresponsive to said generator for producin'gialsweep drive signal'forcontrol of a utilization device, a voltage regulating tube having itsplate circuit 2,574,732 i Denton Nov,'13, 1951 10 ,587,3 3 'Gfu'ndmannFeb. '26, 19.52 2,654,855 *Demon Oct. s, 1953 2 657433 Haantjes' et al.Oct 2 7,1 1953

